The present invention relates to a disk memory or storage device, such as fixed disk device, having a non-volatile memory built in association with a processor thereof, in particular a system for setting or starting the disk storage device when a host computer is started, and a data reading/writing system for exchanging data between the host computer and the disk storage device as a peripheral storage device of the host computer.
A disk memory or storage device, which is employed as a built-in or peripheral large capacity storage device of a computer, is started in association with the computer, since the disk storage device memorizes, as is well known, a basic program including an operating system or the like which is a software pertinent to the basic operations of the computer. After the OS (operating system) or DOS (disk oriented operating system) is set up in the computer, the disk storage device starts reading/writing operation of data on the basis of a command or designation from the computer. Operations of the disk storage device at the time of starting and data reading/writing are outlined below, though the operation is well known.
The disk memory or storage device starts together with the computer. Namely, the disk storage device connected to a power supply self-inspects its electronic circuits, then drives a spindle motor to start rotating its disk and checks whether the disk reaches a normal rotation rate. At this stage, the disk storage device is ready to execute reading/writing operation. However, when the disk storage device is associated with the computer, since the contents designated by the computer are permanently memorized in the disk as setting data for the type of devices or individual devices, if the contents in the disk storage device are not reads out, the operation can not be actually carried out. Thus, after reading the setting data in a processor of the disk storage device, a message of completion of the preliminary operation is sent to the computer.
On the other hand, after power is supplied to the computer, the computer reads out its basic input/output system (hereinafter referred to as BIOS) or an input/output control program (hereinafter referred to as IO control) from a read only memory (hereinafter referred to as ROM), executes self-inspection, and then waits for the above completion message from the disk storage device. As soon as the computer receives the completion message, the computer contacts the disk storage device, and reads out the basic program including the aforementioned IO to load in the computer. Thus, the starting operation of the computer and disk storage device is completed.
When the data is read and written, reading/writing command is supplied from the computer. Since the disk storage device stores, in a specific zone of the disk, so-called directory data indicative of a head address or the like of every data or files stored in the disk storage device, when the reading/writing command is received, the directory data relative to the designated data is read from the specific zone, and then the reading/writing operation for the designated data is carried out in a region of the disk having the address.
In case of reading data, it is not necessary to rewrite the directory data. However, in case of rewriting data and if the directory data to be written is different from the old data, the directory data is rewritten. Of course, when new data is written, the disk storage device stores the directory data in the specific region.
The disk memory or storage device according to the prior art requires considerably long time in starting its operation in the above described manner. Thus, it has been requested to shorten the starting time. Also, so-called access time of the disk storage device measured from the computer, from receiving of a command to a completion of the operation, is long. Thus, it has been requested to shorten the access time.
In a long case, it takes about 10 second to start the disk storage device. In a note type or wrap top type computer that employs a cell as a power supply and connects and disconnects the power supply quite intermittently so as to extend life of the cell, it wastes at every starting operation the corresponding preliminary operation time, which has been required to at least half time. In order to satisfy the requirement, it is effective to shorten the self-inspection period and the preliminary setting period for the disk rotation, but those shortening of operation periods are not enough, in practice, to halve the starting time.
In regard to the reading/writing, since the reading/writing operation is executed much more frequently than the starting operation of the disk storage device, the access time described above is strongly required to be reduced. For this purpose, it is effective to shorten the time for moving a read/write head to a desired track and positioning the track stably thereon by improving an actuation system or positioning system of the read/write head. The access time may be shortened by up to several percent, but it is quite hard to shorten the access time more than 10% by the improvement of the actuation or positioning system.
In view of the foregoing, an object of the present invention is to shorten the starting time and access time at the data reading/writing operation, which occupy most parts of the waste time of the disk memory or storage device viewed from the computer side.